KIEV (Reuters) — Ukraine's embattled
President Viktor Yanukovich on Friday signed into law an amnesty for
demonstrators detained during mass unrest and repealed anti-protest
legislation, in a fresh bid to take the heat out of the political
crisis.

But the move by Yanukovich, which demonstrated he remains
politically active despite going on sick leave on Thursday, was not
likely to be enough to end the sometimes violent anti-government
protests on the streets of Kiev and other cities.

And TV coverage of a prominent opposition activist showing marks of
torture inflicted by mystery kidnappers — along with reports police
tried to arrest the man in hospital — fuelled anger that has become
so explosive that the army made a rare statement, calling for urgent
moves to ease the tension.

Many protesters rejected Yanukovich's amnesty outright, because it
is conditional on occupied buildings being cleared of activists, and
a radical Ukrainian nationalist group behind much of the violence
pressed new tough demands on Friday.

The 63-year-old leader, who looks increasingly isolated in a
tug-of-war between the West and Ukraine's former Soviet overlord
Russia, suddenly withdrew from view on Thursday, complaining of a
high temperature and acute respiratory ailment. He was not seen in
public on Friday.

Opposition leaders, citing fears for demonstrators' health from
Arctic temperatures, urged their supporters not to take to the
streets in large numbers for weekly rallies on Sunday.

But with some television channels replaying repeated video of
opposition activist Dmytro Bulatov, abducted a week ago, displaying
wounds inflicted by his assailants, fury at the government shows no
sign of letting up.

"There's no point in signing this amnesty law," said Olena, working
at an improvised clinic at Kiev's occupied city hall.

"No one will leave here until this government is gone."

The uncompromising standoff, triggered by Yanukovich's decision in
November to accept a $15-billion loan package from Russia instead of
a trade deal with the European Union, prompted a rare intervention
from the military on Friday.

The Defense Ministry urged the president, as commander in chief, to
move swiftly, and within the law, to end the crisis.

"The military and the Ukrainian armed forces ... called on the
supreme commander to take immediate steps, within the framework of
the law, to stabilize the situation in the country and reach
agreement with society," it said in a statement.

Earlier this week, Ukraine's first post-Soviet president warned that
the country was on the brink of "civil war".

The military has emphasized its unwillingness to take sides
throughout the unrest and seems concerned not to be drawn in. In
covering Friday's statement, a Defense Ministry news website quoted
one retired admiral, Serhiy Rybak, recalling Ukrainian troops' roles
in peacekeeping after civil wars abroad: "No political ambition is
worth a drop of human blood," he said.

NATO Secretary General Anders Fogh Rasmussen tweeted that he was
"very concerned by attempts to involve the military in the crisis"
and added that the "military must remain neutral".

At least six people have been killed, all in the past two weeks, and
hundreds more injured in street battles between anti-government
demonstrators and police, which have escalated sharply after the
authorities toughened their response.

KERRY TO MEET OPPOSITION

The crisis forced Prime Minister Mykola Azarov to resign this week,
and as yet there is no sign of a successor. Serhiy Arbuzov, Azarov's
first deputy and a close family friend of Yanukovich, has stepped in
as interim prime minister.

Underlining its economic leverage over Ukraine, Moscow says a new
government must be in place before it goes ahead with a planned
purchase of $2 billion of Ukrainian government bonds.

That reluctance, and the turmoil more generally, contributed to a
2.5 percent fall in the value of the hryvnia currency against the
dollar on Friday to its lowest level for 4-1/2 years.

U.S. Secretary of State John Kerry plans to meet opposition leaders,
including boxer-turned-politician Vitaly Klitschko, on the sidelines
of a security conference in Munich on Friday.

"Our message to Ukraine's opposition will be the full support of
President Obama and of the American people for their efforts," Kerry
said in Berlin on Friday before the meetings.

"But we will also say to them that if you get that reform agenda...
we would urge them to engage in that because further standoff, or
further violence that becomes uncontrollable, is not in anybody's
interests."

Kerry also called on Russia to keep its distance.

"We would ... say to our friends in Russia this does not have to be
a zero (sum) game, this is not something where Ukraine should become
a proxy and trapped in some kind of larger ambition for Russia or
the United States."

The United Nations' human rights office called for an investigation
into reports of kidnappings and torture, and European Union foreign
policy chief Catherine Ashton said she was appalled by signs of
torture inflicted on Bulatov.

"All such acts are unacceptable and must immediately be stopped,"
she said in a statement.

A far-right nationalist group called Right Sector, seen as being
behind violent clashes with police in Kiev, meanwhile demanded the
release of activists held by police, threatening to take the law
into their own hands to free their comrades.

"If they refuse, appropriate steps will be to taken to free these
people and not only constitutional methods will be used," Right
Sector leader Dmytro Yarosh told reporters.

Right Sector, a paramilitary group whose violent actions have
appalled opposition leaders and peaceful protesters, also said it
wanted to play a direct role in any negotiations for a settlement
between Yanukovich and opposition leaders, he said.

(Additional reporting by Pavel Polityuk and Natalia Zinets in Kiev,
Michelle Martin and Gareth Jones in Berlin and Adrian Croft in
Brussels; writing by Mike Collett-White and Alastair Macdonald;
editing by Andrew Heavens)